Electroencephalographic hyperscanning was used to investigate interbrain synchronization patterns in dyads of participants interacting through speech. Results show that brain oscillations are synchronized between listener and speaker during oral narratives. This interpersonal synchronization is mediated in part by a lower-level sensory mechanism of speech-to-brain synchronization, but also by the interactive process that takes place in the situation per se. These results demonstrate the existence of brain-to-brain entrainment which is not merely an epiphenomenon of auditory processing, during listening to one speaker. The study highlights the validity of the two-person neuroscience framework for understanding induced brain activity, and suggests that verbal information exchange cannot be fully understood by examining the listener’s or speaker’s brain activity in isolation.

“The rhythms of brainwaves between two people taking part in a conversation begin to match each other. (…) According to scientists, this interbrain synchrony may be a key factor in understanding language and interpersonal communication. Until now, most traditional research had suggested the hypothesis that the brain ‘synchronises’ according to what is heard, and correspondingly adjusts its rhythms to auditory stimuli.

Now, the experts from the Donostia-based research centre have gone a step further and simultaneously analysed the complex neuronal activity of two strangers while holding a dialogue for the first time.”

“(…) the neuronal activity of two people involved in an act of communication ‘synchronise’ in order to allow for a ‘connection’ between both subjects. (…) It involves interbrain communion that goes beyond language itself and may constitute a key factor in interpersonal relations and the understanding of language (…).”

“Thus, the rhythms of the brainwaves corresponding to the speaker and the listener adjust according to the physical properties of the sound of the verbal messages expressed in a conversation. This creates a connection between the two brains, which begin to work together towards a common goal: communication. The brains of the two people are brought together thanks to language, and communication creates links between people that go far beyond what we can perceive from the outside (…) we can find out if two people are having a conversation solely by analysing their brain waves.”

“Following a script, the dyads held a general conversation and took turns playing the roles of speaker and listener.

Through electroencephalography (EEG) (…) the scientists measured the movement of their brainwaves simultaneously and confirmed that their oscillations took place at the same time. To be able to know if two people are talking between themselves, and even what they are talking about, based solely on their brain activity is something truly marvellous. Now we can explore new applications, which are highly useful in special communicative contexts, such as the case of people who have difficulties with communication (…).”

“In the future, the understanding of this interaction between two brains would allow for the comprehension and analysis of very complex aspects of the fields of psychology, sociology, psychiatry, or education, using the neural images within an ecological or real-world context. Demonstrating the existence of neural synchrony between two people involved in a conversation has only been the first step (…) there are many unanswered questions and challenges left to resolve.

(…) the practical potential of the study is enormous. Problems with communication occur every day. We are planning to get the most out of this discovery of interbrain synchronisation with the goal of improving communication (…).”

The present study investigates brain-to-brain coupling, defined as inter-subject correlations in the hemodynamic response, during natural verbal communication. We used functional near-infrared spectroscopy (fNIRS) to record brain activity of 3 speakers telling stories and 15 listeners comprehending audio recordings of these stories. Listeners’ brain activity was significantly correlated with speakers’ with a delay. This between-brain correlation disappeared when verbal communication failed. (…) Our findings suggest that fNIRS can be used for investigating brain-to-brain coupling during verbal communication in natural settings.

I den amerikanske undersøgelse fik både taler og lytter hovedbånd på, mens de kommunikerede. Undersøgelsen viste, at “a listener’s brain activity actually mirrors the speaker’s brain when he or she is telling story about a real-life experience. And higher coupling is associated with better understanding.”